A. Field of the Invention
The present invention relates most generally to testing and inspection apparatus, and more particularly, to a testing apparatus to inspect sensor assemblies carried by a tray for use with a microwave oven to determine if the sensor assembly is properly assembled and positioned.
B. Description of the Prior Art
In institutions, such as hospitals, it is desirable to provide a system whereby a complete meal may be brought up to serving temperature in a single, quick operation. If this can be done, the meals may be prepared in assembly line fashion on week days during normal working hours, and then they may be kept refrigerated until the time when they are to be served.
An electromagnetic heating system to selectively heat various elements of a load, such as a complete meal or the like, in a single operation, to satisfy institutional feeding needs or requirements is described in U.S. Pat. No. 3,854,021 which issued to Donald G. Moore et al on Dec. 10, 1974 and U.S. Pat. No. 3,854,022 which issued to Donald G. Moore Dec. 10, 1974, and these patents are hereby incorporated by reference for all purposes. Further the above identified copending patent application describes an improved tray construction and sensor assembly for use in a microwave oven.
During the assembly of the sensor device in the tray, it is possible and statistically probable that certain errors and unacceptable assemblies will result. For example, the ferromagnetic annular shaped member may be omitted or an electrically conductive nonmagnetic control disc which is positioned on the bottom plane of the ferromagnetic element, may be omitted or positioned on the wrong surface of the ferromagnetic element. It is also possible that ferromagnetic members may be placed in the wrong relative position within the housing of the sensor assembly. In addition, it may be desirable to assemble sensor assemblies on a standard tray with different materials and relative positioning of component parts to achieve various desired effects due to different energy levels and applications. All these improperly assembled or alternatively positioned combinations will result in the sensor assembly operating adversely when the tray is placed in a microwave oven since the position of the sensor relative to the tray is quite critical. The result with an improperly positioned sensor would be that the articles to be heated would be too hot or too cold or possibly the heating cycle would not be initiated.
To avoid such results, it would be desirable to test or inspect the trays after the sensor has been assembled thereon to determine that the sensor has been accurately located in the tray and hence will function properly when placed in a particular microwave oven.